1, different scoring standards
First of all, we can look at the color and clarity classification of loose diamonds in GIA and national inspection certificates:
The color of GIA loose diamonds from high to low is: D/E/F/G/H/I/J/K/L/M/N/O/P/Q/R/S/T/U/V/W/X/Y/Z.
GIA clarity from high to low: fl/if/vvs1/vvs2/vs1/vs2/si1/si2/i1/I2/i3.
Color of national inspection from high to low: D/E/F/G/H/I/J/K/L/M.
The purity of national inspection is from high to low: LC/vvs1/vvs2/vs1/vs2/si1/si2/p1/p2/P3.
2. Different detection methods
Gia is the most authoritative diamond appraisal institution in the world, and the national inspection is the most authoritative jewelry appraisal center in China. The testing standards of the two institutions are not exactly the same, and the testing methods are slightly different. Therefore, the test results will be slightly different, and the national inspection may be lower or higher than gia.
3. Different testers
The grading of diamonds is evaluated and confirmed by the naked eyes of the inspectors, which has a certain relationship with the staff's mood and fatigue, and subjective factors will affect the testing results.
Extended data:
Internationally recognized diamond grade certificates are as follows:
1.？ International Gemological Institute (IGI) ——IGI Diamond Grade Certificate
IGI, the International Gemological Institute, is the world's largest independent gemological identification laboratory and gemological research and education institution. It has 65,438+05 laboratories and schools in major diamond trading centers and central cities around the world (Antwerp, new york, Toronto, Dubai, Tokyo, Hongkong, Tel Aviv, Los Angeles and Mumbai), and gemologists from more than 96 countries around the world receive laboratory, education and scientific research services from IGI.
Rich experience, professional advice and long-term reputation for reliability and integrity make IGI synonymous with reference standards in jewelry industry. As the largest independent laboratory in the world, IGI has developed patented technologies such as laser lettering and darkroom photos, which have been appraised for decades, and initiated and popularized the 3EX cutting evaluation system. For a long time, it has been a global leader and norm-setter in the field of gemology.
2.？ Gemological Institute of America (GIA) ——GIA Diamond Grade Certificate
Gemological Institute of America is an independent non-profit organization. As one of the world authorities, its certificate enjoys a high reputation in the world. The college's breakthrough research and its own education, experiment and equipment research and development process have witnessed the growth chronicle of the jewelry industry.
GIA diamond classification report and GIA diamond processing are considered as world-famous gem certificates. Diamonds of all shapes and sizes are sent from all over the world to the college for analysis and classification.
3.？ Belgian Diamond High Council -HRD Diamond Grade Certificate
The Belgian Diamond High Council is officially recognized as representing the Belgian diamond trading industry. Its headquarters is located in Antwerp, the world diamond center. HRD diamond color certificate focuses on color description, color design, luminescence and other detailed features that determine the value of colored diamond, which plays an important role in detecting whether diamonds are natural colored diamond or imitation diamonds.
4.？ American Gemological Society -AGS Diamond Grade Certificate
American Gemological Society leads the industry by strict grading standards and providing detailed information. Primary consumers can understand the classification of diamonds with simple numbers and methods. Diamond wholesalers and processors often use the detailed diamond information provided by AGS certificates to buy diamonds in batches around the world.
5.？ European Gemological Institute -EGL Diamond Grade Certificate
EGL was established in 1974, and its customers are mainly professional wholesalers, retailers and cutting factories. Its mission is to help consumers buy diamonds and precious stones.
In the United States and Belgium, EGL certification has a certain professional status and popularity. The appraisal certificate issued by it is enough to provide all the information of diamonds, including physical properties such as weight, color, clarity and size, for the reference of industries and consumers. In 2008, EGL established an independent third-party diamond appraisal laboratory in Hong Kong, named EGLAsia, to provide safer and faster diamond appraisal services for Asian diamond customers. EGL Asia has set up two offices in Chinese mainland: the Shanghai office and the Shenzhen office.
References:
Diamond Certificate-Baidu Encyclopedia